ncargs is set to a very low value at OS. It should be around 128. ncargs system attribute must be set to a high value. The ncargs attribute controls the maximum command line length, including environment variables, on AIX nodes.

$ lsattr -EH -l sys0 |grep ncargs

ncargs 6 ARG/ENV list size in 4K byte blocks True

Run the following command to increase ncargs system attribute
e.g
/usr/sbin/chdev -l sys0 -a ncargs=128
You should get something like this:
ncargs 128 ARG/ENV list size in 4K byte blocks True